The present invention relates generally to microwave amplifiers and more particularly to a microwave amplifier combining two or more tubes in parallel.
There are many applications in radar, communications and electronic warfare that require high power microwave signals whose amplitude can be precisely varied over a given range of values. Due to the nonlinear characteristics of available high power amplifiers (tubes), precise control of the output signal amplitude by varying the amplitude of the low power input signal is often not feasible over the frequency range of operation required. An alternative approach that has been utilized is to operate the high power amplifier at/near saturation and attenuate/modulate the output signal by use of a high power electronically controllable attenuator. Such an attenuator/modulator dissipates power (has loss) even in its lowest attenuation state, thus the efficiency of the combination of amplifier and attenuator/modulator is less than that of the amplifier alone.
Existing parallel tube amplifiers have also been utilized as combination amplifier switches; however such usage has been limited by poor switch isolation (power delivered to undesired output ports).